Synthetic Semaglutide vs Wegovy

A randomized phase 3 trial conducted at 21 Indian centers found a test formulation of synthetic semaglutide non-inferior to Wegovy for percentage change in body weight at 24 weeks. Mean weight change was 13.8% with the test product and 14.1% with the reference product in the primary per-protocol analysis. The least-squares mean difference was 0.26 percentage points, with a 95% confidence interval from -0.86 to 1.39^[1]. The upper bound stayed below the trial's prespecified 4.5-point non-inferiority margin.

That result answers a formulation-comparison question. It does not retest whether semaglutide works better than no active treatment, because both groups received semaglutide. Sun Pharmaceutical Industries manufactured the chemically synthesized test injection, while Wegovy served as the active reference. The paper says the test product had previously met pharmacokinetic bioequivalence criteria and had an identical primary molecular structure in analytical testing^[2]. Regulatory interchangeability is a separate decision for the relevant authority.

What the trial compared

Investigators screened 319 adults and randomized 267 in a 2:1 ratio: 177 to the test product and 90 to Wegovy. Participants were 18 to 65 years old and had a body mass index of at least 30, or at least 27 with hypertension, dyslipidemia or type 2 diabetes. Seventy-one participants had type 2 diabetes. All sites were in India, and treatment ran for 24 weeks with a safety follow-up at week 28^[2].

The study was randomized and active-controlled, but open-label. Participants and investigators knew which product was assigned because the delivery devices differed. Both groups used once-weekly injections with dose escalation toward 2.4 mg, and both received diet counselling plus encouragement to complete at least 150 minutes of physical activity each week^[2]. Those are trial procedures, not instructions for an individual.

The primary endpoint was percentage change in body weight from baseline at week 24. The trial used the per-protocol population for its primary efficacy analysis, meaning participants with major protocol deviations were excluded. An intention-to-treat analysis covering randomized participants served as supporting evidence. Non-inferiority would be declared if the upper end of the two-sided 95% confidence interval for test minus reference remained below 4.5 percentage points^[2].

What non-inferiority means here

A non-inferiority trial asks whether a new product performs no worse than an established comparator by more than an agreed margin. It is not designed to prove the products are identical in every outcome. Here, a difference favouring Wegovy could still satisfy the trial if the confidence interval ruled out the test product being more than 4.5 percentage points worse on the primary weight endpoint.

The observed interval was comfortably inside that boundary. In the per-protocol analysis, mean percentage weight loss was 13.8% with test semaglutide and 14.1% with Wegovy. In the intention-to-treat analysis, the corresponding figures were 13.6% and 13.7%, with an estimated difference of 0.19 points and a 95% confidence interval from -0.95 to 1.33^[2]. Agreement between the two analyses makes the primary finding less dependent on one population definition.

At week 24, 96.4% of test-product participants and 98.8% of reference participants in the reported analysis had lost at least 5% of baseline weight. The proportions losing at least 10% were 80.6% and 80.0%^[1]. Waist circumference, body mass index and the total SF-36 score changed by similar amounts between groups. These secondary comparisons support similarity over six months, but they were not the statistical basis for the main non-inferiority claim.

How this differs from STEP 1

STEP 1 established semaglutide's efficacy against placebo over 68 weeks in 1,961 adults without diabetes. Mean weight change was 14.9% with semaglutide and 2.4% with placebo^[3]. The Indian trial was smaller, shorter and designed around comparison with an active semaglutide product. Similar weight loss across two active arms should not be read as a new estimate of effect versus lifestyle intervention alone.

The populations also differ. The Indian study included adults with and without type 2 diabetes and recruited only in India. Its mean baseline weight was about 93 kg, and the average age was around 41 to 43 years^[2]. STEP 1 excluded diabetes and followed participants nearly three times as long. Cross-trial comparisons can provide context, but they cannot replace a randomized head-to-head test under the same conditions.

Safety and immunogenicity findings

Treatment-emergent adverse events were reported in 72.3% of participants receiving test semaglutide and 76.7% receiving Wegovy. Gastrointestinal complaints were most common. Vomiting, diarrhea and nausea were the leading events in the test group, while diarrhea, vomiting and nausea led in the reference group. Most events were mild or moderate^[2]. The trial was too small and brief to establish equivalence for uncommon or delayed harms.

Three serious adverse events required hospitalization: spinal osteoarthritis in the test group, judged unrelated to study treatment, plus gastritis and acute pancreatitis in the reference group, both judged probably related. One participant in the test group and four in the reference group discontinued because of adverse events. No participants tested positive for anti-drug antibodies at baseline or week 24^[2]. The authors themselves caution that the short exposure limits what the immunogenicity result can show.

The current Wegovy label covers a much larger evidence base and lists warnings that a 267-person comparison cannot meaningfully reassess, including pancreatitis, acute gallbladder disease and severe gastrointestinal adverse reactions^[4]. Readers can find that broader context in our semaglutide safety overview and semaglutide evidence guide.

The limitations that matter

Open-label assignment could affect subjective outcomes and adverse-event reporting, even though body weight is an objective measurement. The 24-week duration does not establish durability, maintenance after treatment, long-term cardiovascular effects or rare-event safety. All participants came from Indian centers, which gives useful regional evidence but limits assumptions about other populations. Sun Pharma funded the study, contributed to its design and analysis, and employed six authors^[2]. Investigator sites received grants from the sponsor.

The choice of a 4.5-point margin also deserves scrutiny. It was set below a cited threshold for clinically important weight loss, yet it remains a judgement about how much difference the trial was willing to exclude. The measured interval was much narrower than the margin, which strengthens the result for the endpoint studied. It does not convert six months of comparative data into proof of identical long-term benefit and risk.

What we still do not know

Longer follow-up is needed to test whether the weight trajectories stay aligned, whether discontinuation patterns remain similar and whether uncommon adverse events differ. This trial did not measure body composition, so it cannot separate fat loss from lean-mass change. It also cannot decide approval, substitution or availability in any country. Those questions belong to regulators and current product information, not to efficacy results alone.

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